Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!usc!ginosko!aplcen!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: sizeof struct
Keywords: sizeof struct
Message-ID: <10945@smoke.BRL.MIL>
Date: 6 Sep 89 10:06:17 GMT
References: <29722@pbhya.PacBell.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 15

In article <29722@pbhya.PacBell.COM> afh@PacBell.COM (Alan Hobesh) writes:
>The following c code prints the size of the definded structure to be 44,
>when compiled on an AT&T 3B20 running UNIX V5.2.1.
[...]
>However, when the code is downloaded to a PC and compiled using Turbo C,
>the size of the structure is reported to be 42.
>Why is there a difference and which is the correct size?

Both sizes are correct.  The difference is due to structure padding
(probably at the end of the structure, in this particular case).
C implementations differ in the amount and location of such padding.
If you intended the structure to describe an externally-imposed data
format, you need to be aware that there may be padding between the
structure members as well as at the end, so a simple roll-in of the
data into such a structure variable may not work right.